A conventional automotive ignition system is shown in FIG. 1. In this system, a microprocessor-based ECU (Electronic Control Unit) 10 receives inputs from a sensor 12, and typically from one or more additional sensors within an automobile, for generating a spark command signal which is calculated to cause a spark to fire at a desired time. An output driver 14 responds to the spark command signal by energizing a high voltage system 16 (typically including an ignition coil) which causes one or more selected spark plugs to fire.
A problem with this conventional system arises as the high voltage system and/or the spark plugs change their characteristics, either because of aging or inherent defects. If, for example, the spark plugs become partially fouled, they probably will not fire at the proper time. A late or an early firing of one or more of the spark plugs can result in degraded combustion, excessive pollutants in the exhaust, and generally degraded performance.